1.1 About this manual
This manual is based on the apparent need of capacity building of Afghan engineers dealing with planning, design, construction, operation and maintenance of large irrigation schemes in Afghanistan. lts preparation is based on ToR which is emphasising the design, especially of the headworks (diversion weirs and intakes).
The ToR specifies the following:
“..Government In recent days is giving higher priority to the development of large-scale irrigation systems for rapid transformation of agricultural sector…”
- review of literature on available standard manuals, study of ongoing design practices, and design standards like those of United States Bureau of Reclamation (USBR), FAO;
- manuals, relevant American Concrete Institute (ACI) and Indian Standard (IS) codes;
- finalization of key structures and preparation of designs elements of irrigation infrastructure such as river diversion structures and canal;
- conveyance structures, different types of pressurized, and non-pressurized (gravity) pipeline bulk water supply and cross drainage;
- structures (are also part of conveyance);
- preparation of a list of irrigation infrastructure, their applicability in various hydro-geological contexts and identify their design approaches, and principals;
- consideration of various design aspects such as hydrological, geological, hydraulics, structural, and construction requirements, etc.
- preparation of draft manual, organize consultations, and validation workshops, finalize the manual and trained 20 NWARA staffs.
- the design manual must include hydraulic computation, structural design considerations, and geotechnics for each of the structures; and
- any other relevant tasks assigned by Food and Agriculture Organization Representative (FAOR), national project manager (NPM), national project coordinator (NPC), and lead technical officer (LTO).
The emphasis of this manual is on large-scale irrigation components that are not sufficiently covered by other, readily available manuals, especially those that were already prepared for Afghan authorities or those prepared by FAO in the past. Therefore, this manual concentrates on large-scale irrigation river diversion or intake and primary conveyance systems. Some important topics, such as irrigation water needs, secondary and tertiary canals, distribution networks, etc. that were well covered elsewhere, will only be mentioned and briefly discussed, providing useful literature and links to some important documents that deal with those topics.